Wind-induced plume and bloom intrusions into Willapa Bay, Washington

The physical oceanography and chlorophyll distribution in Willapa Bay and the adjacent coastal ocean were measured during an upwelling-downwelling wind cycle in late May 1999. Coastal conditions were determined shipboard during two sets of five cross-shelf transects conducted 4 d apart, and instrument moorings simultaneously recorded wind velocity in the nearshore zone and biophysical water properties within Willapa Bay. The results demonstrate that estuarine physical oceanography and chlorophyll concentrations were determined by processes occurring in the nearshore ocean, and these in turn were forced by variation in wind stress. At the start of the study period, southerly winds produced downwelling conditions that forced the Columbia River plume against the coast, and low salinity water was advected into Willapa Bay. This water was relatively low in chlorophyll (